1. Field of the Invention
The present invention relates to a method for transmitting data and a system and terminal using the same, and more particularly, to a method for transmitting data in a General Packet Radio Service (GPRS)/Enhanced Data for Global System for Mobile (GSM) Evolution (EDGE) based communication system.
2. Description of the Related Art
GPRS is a 2.5-Generation (2.5G) mobile telephone technology enabling ultra high-speed Internet and video communication. EDGE is a 2.5G GSM communication technology. GPRS provides a higher transmission speed than an earlier 2nd-Generation (2G) mobile telephone technology and enables connections to the Internet, etc., any time using a packet switched technology.
FIG. 1 is a diagram illustrating a scheme of transmitting a downlink dummy control block according to the conventional art.
A Base Station (BS) broadcasts downlink dummy control blocks to a plurality of Mobile Stations (MSs) located within its own coverage.
The downlink dummy control blocks are used to allocate an Uplink State Flag (USF) in an uplink Temporary Block Flow (TBF) mode following channel dynamic allocation. Also, the downlink dummy control blocks are one type of dummy control block transmitted when a downlink TBF is established but there is no longer a Radio Link Control (RLC)/Medium Access Control (MAC) block.
A downlink channel is a channel used for transmission from a BS to an MS, and an uplink channel is a channel used for transmission from an MS to the BS. Each of the downlink dummy control blocks includes USF information. The MS refers to the downlink is dummy control block when communicating with the BS over an uplink channel.
There are several MSs within a coverage area or cell of one BS. The BS transmits a downlink dummy control block including a USF to the MSs within the cell several times per second because of a frequent change of a channel use state of each MS.
As shown in FIG. 1, MS A, MS B, MS C, and MS D are within a coverage area of the BS. The MSs are assigned USF numbers USF#1, USF#2, USF#3, and USF#4, respectively.
MS A refers to a block burst #1 of downlink dummy control blocks, broadcast from the BS, in order to perform an uplink communication with the BS. Through coding, block bursts #1 becomes a downlink RLC/MAC control block. A description of the downlink RLC/MAC control block is made below in detail with reference to FIG. 2.
MS B may refer to block bursts #2 of the downlink dummy control block to perform an uplink data communication with the BS.
FIG. 2 is a diagram illustrating an example of a downlink dummy control block according to the conventional art.
As shown in FIG. 2, the downlink dummy control block includes an MAC header and a plurality of octets. The MAC header includes a Payload Type (PT) 20, a Relative Reserve Block Period (RRBP) 21, a Supplementary Polling (S/P) 22 and a USF 23. The configuration of the MAC header is defined in the GSM 44.060 standard specification.
The PT 20 indicates whether or not a block broadcast from a BS to an MS is a data block or a control block. The RRBP 21 contains information on a time at which an MS is to respond to whether or not the MS receives a signal from the BS. The S/P 22 contains information on whether or not the RRBP 21 is activated. The USF 23 contains a state flag that the MS refers to when performing uplink data communication with a BS as described in FIG. 1.
In FIG. 2, “RBSN,” “RTI,” “FS,” “AC,” “PR,” “TFI” and “D” are parameters optionally included in the downlink dummy control block.
Control message contents are added to a rear field of the MAC header of the downlink dummy control block. A configuration scheme of the control message contents in GPRS/EDGE based communication is described below.
< Message Type : bit (6) >< Packet Downlink Dummy Control Block message content > ::=< PAGE_MODE : bit (2) >{ 0 | 1 <PERSISTENCE_LEVEL : bit (4) > * 4 }< padding bits >! < Distribution part error : bit (*) = < no string > > ;
Referring to the configuration scheme of the control message contents and FIG. 2, information on a message type is allocated 6 bits, and information on a page mode is allocated 2 bits. A persistence level 27 is information necessary for an MS to access a network. The control message contents also include a bit 26 for deciding whether or not to insert persistence level information into the downlink dummy control block broadcast by the BS. The persistence level 27 is composed of a combination of four 4-bit strings and therefore, is expressed as “<PERSISTENCE_LEVEL:bit (4)>*4.”
As shown in FIG. 2, all remnant fields are filled with padding bits 28 after the MAC header information, the optionally inserted octet string, the message type, the page mode and the persistence level 27 are inserted into the downlink dummy control block.
The padding bits 28 do not contain special information and are mere fillers for adaptation to a defined frame of the downlink dummy control block. The downlink dummy control block is broadcast from a BS to MSs with the meaningless padding bits 28. Therefore, there is a problem of causing a waste of radio resources allocated to the MSs.
Among recent services provided to MS users, there is a life information service for continuously updating and providing brief news information, weather information, stock price information, etc. and displayed on a part of a display of an MS.
In the life information service, content provided is composed of a small capacity of data and is broadcast from a BS to an MS. However, separate traffic resources have to be allocated for the life information service, and therefore, there is a problem of deteriorating the use efficiency of radio resources.